a) Field of the Invention
The invention relates to a lever aseimatic reflection sheet device and, more particularly, to an aseimatic reflection sheet device used in a vehicle head-up display device, the lever action is applied to improve its aseimatic capacity that it would not be affected by vibration of vehicle dashboard, to thereby improve fastening and supporting stability of the reflection sheet.
b) Description of Prior Art
There are more and more information in vehicle, it is dangerous that drivers usually take their eyes off the road to read information during driving. In order to solve the drawbacks, head-up displays are developed, so that drivers may simultaneously read information and pay attention on the road conditions ahead. Especially the head-up display using concave mirror for imaging, display area may be enlarged and the distance from the displayed image to drivers' eyes is far enough, usually greater than 2 meters. When drivers see the displayed information, focal length of eyes is near drivers' line of sight for watching road conditions, so that drivers may pay attention on the road during reading information, the danger of driving may be reduced significantly.
The virtual imaging is imaged by using a concave mirror, the imaging formula (of concave mirror) is: 1/p+1/q=1/f, wherein f is focal distance, q is object distance, p is image distance. Virtual images may be enlarged in a general magnification, and the distance of virtual image may simultaneously be become farer in the same ratio, between four to six times, thus, readers may be in the best condition. If magnification is too large, readers may feel dizzy easily, so that the distance between the virtual image and drivers' eye may be larger than 2 meters, and the location of image may be in the rear of the reflection sheet with distance larger than 1.2 meters, namely, distance of optical path from display to concave mirror may be larger than 24 cm (if the magnification is five times). Besides, distance of optical path may be increased by reflecting back and forth through mirror surface, but the volume needed by optical path is large, so a space is usually reserved for head-up display device inside the vehicle dashboard.
This method may only be used if the original manufacturer reserves desired space at design time. For the market of installation, the head-up display cannot be installed on the vehicle dashboard because the size is too large with optical path device, even may obstruct drivers' line of sight.
Another solution for optical path device with large size is separating it that the display is fixed on the top of the windshield and the reflection sheet is fixed on vehicle dashboard. However, vehicle dashboards in many vehicles may shock due to rotation of engine or air conditioning compressor, and the reflection sheet fixed on the top may be shocked. Also, the displacement of shocking may be enlarged due to enlarge effect of concave mirror, and displayed image may shocked severely.
In order to solve the problem of the reflection sheet being shocked, the inventor of the present invention refers to the cited references TW publication no. 530961, TW M273183, TW M375372, TW publication no. 576080, TW 1352165, TW M288937, TW M275639 etc., and found that for the problem that the conventional reflection sheet being shocked, the related technical content and applications still have technical bottlenecks.
For the shaking problem of the reflection sheet, although the reflection sheet could be closely against the windshield by elasticity of elastic element to resist inertia of vibration, the effect is limited. Elasticity of the elastic element is not changed, inertia of vibration with different strength is dynamic, thus, the shaking problem could be overcome if elasticity of the elastic element is larger than maximum of inertia of vibration. However, if there is no vibration, elasticity of the elastic element only causes deformation of the reflection sheet, so it is not a good solution.